Coil for electrical apparatus.



No. 873,253. PATENTED DEC. V10, 1907.

P. MA'OGAHAN.

COIL FOR ELECTRICAL APPARATUS. APPLIGATION FILED 00118, 1905.

yWITNESSES: INV NTOR Z QJ a@ ATTORNEY PAUL MACGAHAN, OF PITTSBURG,PENNSYLVANIA, ASSIGNOR TO WESTINGHOUSE ELECTRIC MANUFACTURING COMPANY, A

CORPORATION OF PENNSYLVANIA.

COIL FOR ELECTRICAL APPARATUS.

Specification of Letters Patent.-

Patented Dec. 10, 1907.

Application filed October 18, 1905. Serial No. 283\338.

My inventlon relates to electrical apparatus and, particularly tohelical coils for such apparatus.

he object of my invention is to provide a helical coil of'a small numberofturns which shall exert a uniform, magnetic pull.

In the operation of a solenoid, as ordinarily constructed7 thatcomprises only one or but a few convolutions of a large conductor it hasbeen found that a non-uniform magnetic field is roduced in the interiorspace occu ied by t e core, the denser'portions of the eld beingproduced in proximity to the sides of the lsolenoid where the largernumber of conductors occur. For instance, in a solenoid having but asingle convolution the denser portion of the field occurs near the sidewhere theconductor crosses ,itself at the beginning and ending of theconvolution, f If a magnetizable core movable longitudinally in theinteriorspace it will be drawn to one side so as to operate in thedenser portion of the field. This displacement from an vaxial positionis objectionable in many devices, such, for example, as measuringinstruments. .f A solenoidfconstructed inaccordance with my inventioncomprises a plurality of inter-I v leaved and symmetricajly disposedhelices the corresponding ends, of which are uniformly spaced apart andconnected to suitable ring-shaped terminal pieces. Thenumber ofconductors adjacent all sides of the opening is substantially the sameand the field, consequently, is uniform.

My invention permits of the construction of solenoids having less than asingle convolution'or any full or fractional numbers of convolutionswhich will produce substantiallyuniform fields throughout their interiorspaces.

Figure 1 of the accom anying drawing is l a front elevation of an eectrical measuring instrument having a coil that embodies m f invention.Fig. 2 is a plan view of the coil v shown in Fig. 1 and Fig. 3 is a sideelevation of one section of the coil shown in Figs. '1 and 2.y

in the county of Allegheny and" The casing 1 of the instrument may havea suitable back or base plate 2 upon which are supported the operatingparts of the instrument, these parts comprising a solenoid 3, a core 4,a liexible support 5 for the core, a segmental block 6 to which theflexible support 5 is connected 'and with the curved face of which itengages, an ad`ustable counter weight 7 for the block 6 an a pointer 8,the free end of which moves over a suitable scale 9. The parts justreferred to may be of any well known construction except the solenoid 3,the novel, structural features of which constitute my present invention.The coil 3, instead kof being composed of a single continuous helix, asis usual, comprises a plurality of helices 10, 11` .and 12 that aremterleaved y and symmetrically .disposed and the ends of which are.uniformly spaced apart and .connected to suitable conducting Vrings 13and 14.

While I have here shown the compound helix as composed of threeconstituent helices may be greater or less than three if desired, itbeing essential, however, 1n order to secure thoughout the area of theopening in the solenoid, to uniformly space t e constituent iortions',and obviously the greater. the number of members iemployed' the closerwill be the ap roximation to uniformity in the magnetic field.

I claim as my invention: 1. A solenoid comprising a plurality of in'-terleaved single layer helices of substantially 4equal diameterand-length and connected-in parallel relation. f

2. A solenoid comprising a plurality of interleaved, equally spacedhelices of equal lengthI and conducting rings connecting correspondingends together.

l3. An actuating coil for electrical measuring instruments comprising aplurality of interleaved, helices ofthe same diameter and separatedthroughout by air spaces and means for electrically connectingcorresponding ends together.

4. A multiple solenoid comprising a plurality of helical strap coilssymmetrically disposed and separated from each other by uniform airspaces, and means for connectlng corres onding ends together.

5. n solenoid comprising a plurality of interleaved helices uniformlyseparated from I desire it to be understood that the number substantialuniformity of the `magnetic'ield each other by air spaces and connectedin In testimony whereof,A l llave hereunto parallelrelation. subscribedmy name this 13th day of Octo- 6. A solenoid comprising a plurality ofinber, 1905. terleaved and symmetrically disposed helices PAUL MACGAHAN5 the corresponding ends of which are spaced Wvitnesses:

apart and connected to suitable ring-shaped I S. M. TRUXAL,

terminal nieces. i BIRNEY HINEs.

